import cv2
import numpy as np

drawing = False
mode = True
ix, iy = -1, -1


def nothing(x):
    pass


def draw_circle(event, x, y, flags, param):
    r = cv2.getTrackbarPos("R", "image")
    g = cv2.getTrackbarPos("G", "image")
    b = cv2.getTrackbarPos("B", "image")
    color = (b, g, r)
    s = cv2.getTrackbarPos("eraser", "image")
    if s == 1:
        color = (255, 255, 255)
    thin = cv2.getTrackbarPos("thin", "image")

    global ix, iy, drawing, mode
    if event == cv2.EVENT_LBUTTONDOWN:
        drawing = True
        ix, iy = x, y
    elif event == cv2.EVENT_MOUSEMOVE and flags == cv2.EVENT_FLAG_LBUTTON:
        if drawing:
            if mode:
                cv2.rectangle(img, (ix, iy), (x, y), color, -1)
            else:
                cv2.circle(img, (x, y), thin, color, -1)
    elif event == cv2.EVENT_LBUTTONUP:
        drawing == False


img = np.zeros((512, 512, 3), np.uint8)
img[:] = 255
cv2.namedWindow("image")
cv2.createTrackbar("R", "image", 0, 255, nothing)
cv2.createTrackbar("G", "image", 0, 255, nothing)
cv2.createTrackbar("B", "image", 0, 255, nothing)

cv2.createTrackbar("eraser", "image", 0, 1, nothing)
cv2.createTrackbar("thin", "image", 1, 50, nothing)

cv2.setMouseCallback("image", draw_circle)

while 1:
    cv2.imshow("image", img)
    k = cv2.waitKey(1) & 0xFF
    if k == ord("q"):
        mode = not mode
    elif k == 27:
        break
